This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2020-028301, filed on Feb. 21, 2020, in the Japan Patent Office, the entire disclosure of which is incorporated by reference herein.
Technical Field
Aspects of the present disclosure relate to a drive mechanism rotating a rotator, a fixing device including the drive mechanism, a conveying device including the drive mechanism, and an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction peripheral of the foregoing machines.
Related Art
There is known an image forming apparatus such as a copier or a printer that includes a drive mechanism to rotationally drive a rotator with two motors.
In an aspect of the present disclosure, there is provided a drive mechanism that drives a rotator to rotate including a main motor, an assist motor, and processing circuitry. The main motor drives the rotator. The assist motor drives the rotator and assists a drive of the rotator by the main motor. The processing circuitry controls a speed of the main motor so that a rotational speed of the rotator is constant, and controls a motor voltage of the assist motor so that the motor voltage of the assist motor changes according to a change in a motor current of the main motor.
In other aspects of the present disclosure, there are provided a fixing device, a conveying device, and an image forming apparatus that include the drive mechanism.
The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:
The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted.
In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results.
Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable.
Referring now to the drawings, embodiments of the present disclosure are described below. In the drawings for explaining the following embodiments, the same reference codes are allocated to elements (members or components) having the same function or shape and redundant descriptions thereof are omitted below.
Initially with reference to
The image forming apparatus 1 also includes chargers 12, developing units 13, primary transfer rollers 14, and cleaning units 15. Electrostatic latent images are formed on surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK, and developed into toner images of yellow, magenta, cyan, and black by the developing units 13. The toner images on the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK are transferred to and superimposed on the intermediate transfer belt 17 by the primary transfer rollers 14. Residual (untransferred) toner is collected from the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK by the cleaning units 15. The image forming apparatus 1 further includes a cleaning unit 16, an intermediate transfer belt 17, a secondary transfer roller 18, and a fixing device 20. The cleaning unit 16 cleans the intermediate transfer belt 17. The intermediate transfer belt 17 bears different colors of toner images superimposed one atop another. The secondary transfer roller 18 transfers the toner image from the intermediate transfer belt 17 onto the sheet P as a multicolor toner image. The fixing device 20 fixes the toner image (unfixed toner image) onto the sheet P.
A description is provided below of an operation of a normal color image forming of the image forming apparatus 1. The document conveying unit 3 conveys, with conveying rollers, the document D from a document table onto an exposure glass 5 of the scanner 4. The scanner 4 optically reads the image data of the document D set on the exposure glass 5. The yellow, magenta, cyan, and black image data are transmitted to the writing device 2. The writing device 2 emits laser beams (e.g., exposure light) onto the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK according to the image data of yellow, magenta, cyan, and black, respectively.
Each of the four photoconductor drums 11Y, 11M, 11C, and 11BK rotates counterclockwise in
The laser beam corresponding to the yellow component irradiates the outer circumferential surface of the first photoconductor drum 11Y from the left in
Thereafter, the surface of each of the photoconductor drums 11Y, 11M, 11C, and 11BK bearing the electrostatic latent image reaches a developing position opposite the developing unit 13. The developing units 13 supply toner of the respective colors onto the photoconductor drums 11Y, 11M, 11C, and 11BK and develop the electrostatic latent images on the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK into visible toner images (a development process). After the development process, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK reach positions facing the intermediate transfer belt 17. The primary transfer rollers 14 are disposed at positions where the photoconductor drums 11Y, 11M, 11C, and 11BK face the intermediate transfer belt 17 and in contact with an inner circumferential surface of the intermediate transfer belt 17. At the positions of the primary transfer rollers 14, the respective toner images on the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK are sequentially transferred and superimposed onto the intermediate transfer belt 17 (a primary transfer process).
After the primary transfer process, the surfaces of the respective photoconductor drums 11Y, 11M, 11C, and 11BK reach cleaning positions opposite the respective cleaning units 15. The cleaning units 15 remove and collect the residual (untransferred) toner from the outer circumferential surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK (a cleaning process). Thereafter, the outer circumferential surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK pass through dischargers to complete a series of image forming processes performed on the photoconductor drums 11Y, 11M, 11C, and 11BK.
On the other hand, the multicolor toner image is formed on the intermediate transfer belt 17 by transferring and superimposing the respective single-color toner images on the photoconductor drums 11Y, 11M, 11C, and 11BK. Then, the intermediate transfer belt 17 bearing the multicolor toner image moves clockwise in
The sheet P is conveyed from the sheet feeder unit 7 via the registration roller pair 9 to a secondary transfer nip between the intermediate transfer belt 17 and the secondary transfer roller 18. In detail, a feed roller 8 feeds the sheet P from the sheet feeder unit 7 that accommodates multiple sheets P, and the sheet P is conveyed to the registration roller pair 9 through a conveyance passage. The sheet P that has reached the registration roller pair 9 is conveyed toward the secondary transfer nip, timed to coincide with the arrival of the multicolor toner image on the intermediate transfer belt 17.
A conveyance belt conveys the sheet P, on which the multicolor toner image, in other words, a full-color image has been transferred, to a fixing device 20. The fixing device 20 fixes the multicolor image (toner image T) onto a surface of the sheet P at a nip area (a fixing nip) between a fixing roller 21 and a pressure roller 22 (a fixing process). After the fixing process, an output roller pair ejects the sheet P as an output image outside a main body of the image forming apparatus 1 to complete a series of image forming processes (a print operation).
Referring to
In response to a print command (a print request), the drive mechanism 50 starts rotating the fixing roller 21 clockwise in
The configuration and operation of the drive mechanism 50, which is characteristic of the fixing device 20 (image forming apparatus 1) in the present embodiment, will be described in detail below. As described above with reference to
The drive mechanism 50 rotationally drives the output gear 65 as a rotator. In particular, in the present embodiment, the fixing roller 21 is rotationally driven by the output gear 65 of the drive mechanism 50. Thus, it can be said that the fixing roller 21 is rotationally driven by the drive mechanism 50. As illustrated in
As illustrated in
The first motor gear 61 is disposed on a motor shaft of the main motor 51 and rotated in the counterclockwise direction in
The second motor gear 63 is disposed on a motor shaft of the assist motor 52 and rotated in the counterclockwise direction in
The output gear 65 as a rotator meshes with each of the first small-diameter idler gear 62b and the second small-diameter idler gear 64b. In the present embodiment, the output gear 65 is an idler gear and meshes with a driven gear 27 (see
In the present embodiment, the speed of the main motor 51 is controlled (rotational speed control) so that the rotational speed of the output gear 65 (rotator) is constant. In detail, the target rotational speed of the main motor 51 is stored in the controller 90, and the main motor 51 is driven so that the target rotational speed is equal to the stored target rotational speed. The rotational drive of the main motor 51 is decelerated by the first idler two-stage gear 62 and transmitted to the output gear 65. The speed (rotational speed) of the main motor 51 is detected by an encoder 95 (i.e., a detector that detects the rotational speed of, e.g., the motor shaft of the main motor 51 or the output gear 65). Based on the detection result, the controller 90 adjusts the motor current (main motor current) of the main motor 51 so that the speed of the main motor 51 attains the target rotational speed.
In contrast, in the present embodiment, the assist motor 52 is voltage-controlled so that the motor voltage changes in response to the change of the motor current of the main motor 51. In detail, the main motor 51 is driven at a constant speed so as to attain the target rotational speed of the main motor 51, and the assist motor 52 is driven according to the rotational speed of the output gear 65 while the input motor voltage of the assist motor 52 is adjusted. The rotational drive of the assist motor 52 is decelerated by the second idler two-stage gear 64 and transmitted to the output gear 65.
In detail, when the motor current of the main motor 51 increases, the assist motor 52 is voltage-controlled so that the motor voltage increases. As described above, the motor current of the main motor 51 is adjusted so that the rotational speed of the main motor 51 attains the target rotational speed. The motor current is also adjusted when the load torque is changed. Specifically, when the load torque applied to the main motor 51 increases with the increase of the drive torque of the fixing roller 21, the controller 90 controls the main motor 51 so that the motor current becomes larger than when the load torque is small. In particular, since the fixing roller 21 is heated and thermally expanded by the heater 25 and the drive torque is changeable, the change of load torque of the main motor 51 is likely to occur. The change of the motor current of the main motor 51 is detected by a current detector 91, and the motor voltage of the assist motor 52 is controlled by the controller 90. Specifically, when the motor current of the main motor 51 becomes large, the motor voltage of the assist motor 52 is controlled so as to be larger than when the motor current is small. The motor voltage of the assist motor 52 is detected by a voltage detector 92 and fed back to the controller 90.
In other words, in the drive mechanism 50 according to the present embodiment, the assist amount of assisting the drive of the output gear 65 (rotator) by the main motor 51 is adjusted by the assist motor 52 according to the change in the load torque of the main motor 51. Specifically, when the load torque of the main motor 51 is large, the load torque of the main motor 51 needs to be reduced (in other words, the assist motor 52 needs to assist the drive of the output gear 65). Therefore, the assist amount by the assist motor 52 becomes larger. In contrast, when the load torque of the main motor 51 is small, the load torque of the main motor 51 does not need to be reduced. Therefore, the assist amount by the assist motor 52 becomes smaller.
As illustrated in
According to the present embodiment, the output gear 65 (or fixing device 20) is driven by the speed-controlled main motor 51 and the voltage-controlled assist motor 52. Thus, the load torque applied to the main motor 51 can be reduced, and the rotational speed of the output gear 65 (rotator) rotationally driven by the two motors (i.e., the main motor 51 and the assist motor 52) can be accurately maintained constant. In other words, if each of the two motors is speed-controlled, the respective speed controls may interfere (conflict) with each other, and it may be difficult to maintain the rotational speed of the output gear 65 (rotator) accurately and constantly. In contrast, in the present embodiment, although the main motor 51 is speed-controlled, the assist motor 52 is voltage-controlled so that the motor voltage is adjusted according to the change of the load torque of the main motor 51 in accordance with the rotational speed of the output gear 65. Thus, the above-described disadvantage is reduced.
According to the present embodiment, the output of the main motor 51 is larger than the output of the assist motor 52. That is, the assist motor 52 has a smaller power than the main motor 51. Since the assist motor 52 drives the output gear 65 (rotator) and assists the drive of the main motor 51, such a configuration allows cost reduction and downsizing of the overall drive mechanism 50.
Referring to
Each of the main motor 51 and the assist motor 52 has a rated current and needs to be driven at the rated current or less. If the load of the output gear 65 (driving torque of the fixing device 20) is constant, when the reduction ratio of the assist motor 52 (the reduction ratio of the second idler two-stage gear 64) is small, the range in which each of the main motor 51 and the assist motor 52 can be driven at the rated current or less is narrowed compared with when the reduction ratio is large. The larger the range, the larger the margin in which each of the main motor 51 and the assist motor 52 can be driven at the rated current or less, and the range becomes the adjustment range W in which the motor voltage of the assist motor 52 is available. The load torque of the assist motor 52 is transmitted via the second idler two-stage gear 64 (deceleration mechanism) with the load on the output gear 65 being smaller by the reduction ratio. Accordingly, when the reduction ratio of the assist motor 52 is large, the load torque of the assist motor 52 becomes smaller than when the reduction ratio is small. As a result, the motor current of the assist motor 52 becomes smaller, and the margin for the auxiliary drive is increased. Thus, the adjustment width of the assist amount can be set by the reduction ratio of the assist motor 52. On the other hand, the assist motor 52 has an output efficiency for the rotational speed, and it is desirable to use at a high efficiency. If the rotational speed of the output gear 65 is determined, the rotational speed of the assist motor 52 can be determined by the reduction ratio. Therefore, in consideration of the adjustment width and the output efficiency of the assist motor 52, the reduction ratio of the assist motor 52 is set so that the adjustment range W of the assist amount is not less than the predetermined width Wz.
As illustrated in
First Variation
As illustrated in
In first variation, the motor pulley gear 67 is disposed on the motor shaft of the assist motor 52 and rotated in the counterclockwise direction in
Second Variation
As illustrated in
Third Variation
As illustrated in
As described above, the drive mechanism 50 according to the present embodiment includes the main motor 51 and the assist motor 52. The main motor 51 drives the output gear 65 (rotator). The assist motor 52 assists the drive of the output gear 65 by the main motor 51 to drive the output gear 65. The speed of the main motor 51 is controlled so that the rotational speed of the output gear 65 is constant. The assist motor 52 is voltage-controlled so that the motor voltage changes in response to the change of the motor current of the main motor 51. Thus, the rotational speed of the output gear 65 (rotator) driven by the two motors (i.e., the main motor 51 and the assist motor 52) can be accurately maintained constant.
It is to be noted that, in the present embodiment, the drive mechanism 50 is provided in the image forming apparatus 1 that performs full-color image formation. However, embodiments of this disclosure are not limited to such a drive mechanism in an image forming apparatus that performs full-color image formation. For example, a drive mechanism according to an embodiment of this disclosure may be provided in an image forming apparatus that performs monochrome image formation. Further, it is to be noted that, in the present embodiment, the drive mechanism 50 is provided in the image forming apparatus 1 that employs electrophotography. However, embodiments of this disclosure are not limited to such a drive mechanism provided in an image forming apparatus that employs electrophotography. For example, a drive mechanism according to an embodiment of this disclosure may be provided in an image forming apparatus that employs an inkjet method or a stencil printing machine. Furthermore, in the present embodiment, the fixing roller 21 (fixing rotator) is configured to be rotated by the output gear 65. However, in an embodiment of the present disclosure, the pressure roller 22 (pressure rotator) may be configured to be rotated by the drive transmitted from an output gear. In the present embodiment, the drive mechanism 50 is disposed in the fixing device 20 (or the conveying device 100). However, for example, a drive mechanism according to an embodiment of the present disclosure may be disposed in any other device than a fixing device or a conveying device. Moreover, in the present embodiment, the rotator driven by the drive mechanism 50 is the output gear 65. However, the rotator driven by the drive mechanism 50 is not limited to such an output gear. In some embodiments, the drive mechanism may rotate various types of rotators. In such configurations, similar effects to the above-described embodiments are also attained.
Note that embodiments of the present disclosure are not limited to the above-described embodiments and it is apparent that the above-described embodiments can be appropriately modified within the scope of the technical idea of the present disclosure in addition to what is suggested in the above-described embodiments. Further, the number, position, shape, and so forth of components are not limited to those of the present embodiment, and may be the number, position, shape, and so forth that are suitable for implementing the present disclosure.
Any one of the above-described operations may be performed in various other ways, for example, in an order different from the one described above.
Each of the functions of the described embodiments may be implemented by one or more processing circuits or circuitry. Processing circuitry includes a programmed processor, as a processor includes circuitry. A processing circuit also includes devices such as an application specific integrated circuit (ASIC), digital signal processor (DSP), field programmable gate array (FPGA), and conventional circuit components arranged to perform the recited functions.
Number | Date | Country | Kind |
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2020-028301 | Feb 2020 | JP | national |
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20180334342 | Miyajima | Nov 2018 | A1 |
20190127168 | Miyajima | May 2019 | A1 |
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2010-078083 | Apr 2010 | JP |
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Entry |
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Japanese Office Action dated Oct. 19, 2023 for corresponding Japanese Patent Application No. 2020-028301. |
Number | Date | Country | |
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20210261367 A1 | Aug 2021 | US |